Construction and Evaluation of a Korean Native Microbial Consortium for the Bioremediation of Diesel Fuel-Contaminated Soil in Korea

A native microbial consortium for the bioremediation of soil contaminated with diesel fuel in Korea was constructed and its biodegradation ability was assessed. Microbial strains isolated from Korean terrestrial environments, with the potential to biodegrade aliphatic hydrocarbons, PAHs, and resins, were investigated and among them, eventually seven microbial strains, Acinetobacter oleivorans DR1, Corynebacterium sp. KSS-2, Pseudomonas sp. AS1, Pseudomonas sp. Neph5, Rhodococcus sp. KOS-1, Micrococcus sp. KSS-8, and Yarrowia sp. KSS-1 were selected for the construction of a microbial consortium based on their biodegradation ability, hydrophobicity, and emulsifying activity. Laboratory- and bulk-scale biodegradation tests showed that in diesel fuel-contaminated soil supplemented with nutrients (nitrogen and phosphorus), the microbial consortium clearly improved the biodegradation of total petroleum hydrocarbons, and all microbial strains constituting the microbial consortium, except for Yarrowia survived and grew well, which suggests that the microbial consortium can be used for the bioremediation of diesel fuel-contaminated soil in Korea

Comparative Genomics Reveals Adaptation by Alteromonas sp. SN2 to Marine Tidal-Flat Conditions: Cold Tolerance and Aromatic Hydrocarbon Metabolism

Alteromonas species are globally distributed copiotrophic bacteria in marine habitats. Among these, sea-tidal flats are distinctive: undergoing seasonal temperature and oxygen-tension changes, plus periodic exposure to petroleum hydrocarbons. Strain SN2 of the genus Alteromonas was isolated from hydrocarbon-contaminated sea-tidal flat sediment and has been shown to metabolize aromatic hydrocarbons there. Strain SN2's genomic features were analyzed bioinformatically and compared to those of Alteromonas macleodii ecotypes: AltDE and ATCC 27126. Strain SN2's genome differs from that of the other two strains in: size, average nucleotide identity value, tRNA genes, noncoding RNAs, dioxygenase gene content, signal transduction genes, and the degree to which genes collected during the Global Ocean Sampling project are represented. Patterns in genetic characteristics (e.g., GC content, GC skew, Karlin signature, CRISPR gene homology) indicate that strain SN2's genome architecture has been altered via horizontal gene transfer (HGT). Experiments proved that strain SN2 was far more cold tolerant, especially at 5°C, than the other two strains. Consistent with the HGT hypothesis, a total of 15 genomic islands in strain SN2 likely confer ecological fitness traits (especially membrane transport, aromatic hydrocarbon metabolism, and fatty acid biosynthesis) specific to the adaptation of strain SN2 to its seasonally cold sea-tidal flat habitat

ZHO-1, an intrinsic MBL from the environmental Gram-negative species Zhongshania aliphaticivorans

Objectives: Our aim was to characterize the putative MBL of the environmental strain Zhongshania aliphaticivorans isolated from a marine environment.Methods: The putative MBL was identified in silico using the NCBI database. The β-lactamase gene was cloned into different Escherichia coli backgrounds. Kinetic parameters were determined using the purified enzyme.Results: The enzyme named ZHO-1 shared 51% amino acid identity with the acquired class B carbapenemases IMP-1, KHM-1 and DIM-1. Expression of the blaZHO-1 gene in a susceptible E. coli resulted in a carbapenemase phenotype. Kinetic parameters determined from purified ZHO-1 enzyme showed that it had significant hydrolytic activity against most β-lactams including penicillins, cephalosporins and carbapenems, with the exception of aztreonam and cefepime.Conclusions: This study adds to the knowledge regarding environmental species as a reservoir of possible clinically relevant MBLs

Identification of Trans-4-Hydroxy-L-Proline as a Compatible Solute and Its Biosynthesis and Molecular Characterization in Halobacillus halophilus

Halobacillus halophilus, a moderately halophilic bacterium, accumulates a variety of compatible solutes including glycine betaine, glutamate, glutamine, proline, and ectoine to cope with osmotic stress. Non-targeted analysis of intracellular organic compounds using 1H-NMR showed that a large amount of trans-4-hydroxy-L-proline (Hyp), which has not been reported as a compatible solute in H. halophilus, was accumulated in response to high NaCl salinity, suggesting that Hyp may be an important compatible solute in H. halophilus. Candidate genes encoding proline 4-hydroxylase (PH-4), which hydroxylates L-proline to generate Hyp, were retrieved from the genome of H. halophilus through domain searches based on the sequences of known PH-4 proteins. A gene, HBHAL_RS11735, which was annotated as a multidrug DMT transporter permease in GenBank, was identified as the PH-4 gene through protein expression analysis in Escherichia coli. The PH-4 gene constituted a transcriptional unit with a promoter and a rho-independent terminator, and it was distantly located from the proline biosynthetic gene cluster (pro operon). Transcriptional analysis showed that PH-4 gene expression was NaCl concentration-dependent, and was specifically induced by chloride anion, similar to the pro operon. Accumulation of intracellular Hyp was also observed in other bacteria, suggesting that Hyp may be a widespread compatible solute in halophilic and halotolerant bacteria

Metagenomic analysis of the human microbiome reveals the association between the abundance of gut bile salt hydrolases and host health

Bile acid metabolism by the gut microbiome exerts both beneficial and harmful effects on host health. Microbial bile salt hydrolases (BSHs), which initiate bile acid metabolism, exhibit both positive and negative effects on host physiology. In this study, 5,790 BSH homologs were collected and classified into seven clusters based on a sequence similarity network. Next, the abundance and distribution of BSH in 380 metagenomes from healthy participants were analyzed. It was observed that different clusters occupied diverse ecological niches in the human microbiome and that the clusters with signal peptides were relatively abundant in the gut. Then, the association between BSH clusters and 12 human diseases was analyzed by comparing the abundances of BSH genes in patients (n = 1,605) and healthy controls (n = 1,540). The analysis identified a significant association between BSH gene abundance and 10 human diseases, including gastrointestinal diseases, obesity, type 2 diabetes, liver diseases, cardiovascular diseases, and neurological diseases. The associations were further validated by separate cohorts with inflammatory bowel diseases and colorectal cancer. These large-scale studies of enzyme sequences combined with metagenomic data provide a reproducible assessment of the association between gut BSHs and human diseases. This information can contribute to future diagnostic and therapeutic applications of BSH-active bacteria for improving human health

Special issue on International Biotechnology Symposium, IBS-2012: September 16–21, Daegu, Korea

[Abstract not available